This disclosure relates generally to microelectromechanical (MEMS) devices, and in particular, but not exclusively, relates to MEMS switching apparatus.
The use of microelectromechanical (MEMS) switches has been found to be advantageous over traditional solid-state switches. For example, MEMS switches have been found to have superior power efficiency, low insertion loss, and excellent electrical isolation. However, for certain high-speed applications such as RF transmission/receiving, MEMS switches are in general too slow. This is primarily due to the speed of a MEMS switch being limited by its resonance frequency. To improve the speed of the MEMS switch, the stiffness of the MEMS structure must be increased. However, stiff structures require higher actuation voltages for the switching action to occur.
Current MEMS switches, although functional, do not provide optimum performance because they are not mechanically optimized. Moreover, the lack of mechanical optimization in existing switches means that the switches tend to fail more rapidly. The lack of optimization also leads to degraded performance not only in measures such as switching speed and efficiency, but also in more corollary measures such as the actuation voltage of the switch.
One possible solution is to simply reduce the gap between the structure and the actuation electrode. This is problematical, however, due to degraded electrical isolation arising from coupling between the switch and the electrode. Additionally, the small gap between the structure and the actuation electrode has led to stiction problems between the structure and the electrode.